In the Season 1 premiere of Countdown, a surprise cameo by This Is Us star Milo Ventimiglia sets off a chain of events that drives the plot of the show. Creator Derek Haas reveals that he was lucky to have Ventimiglia on board for the episode.
Ventimiglia plays Darden, an agent at the Department of Homeland Security, in the opening scene. He is swiftly killed, but his character’s actions set off a murder investigation that brings together a task force led by Blythe (Eric Dane). As they dig deeper, they uncover evidence that suggests one of Darden’s coworkers was involved with a cartel.
The widow, however, refuses to believe her husband could have been dirty. The task force’s investigation proves she is right, and it turns out Darden had been investigating his coworker when he was killed. Despite the brief appearance, Ventimiglia’s character plays a crucial role in setting off the events of the show.
The surprise cameo is just one example of how Countdown is creating an “Avengers”-like team of characters, with a diverse group of actors bringing together to solve a complex crime. With its blend of action and suspense, Countdown is an exciting new series that fans of crime thrillers won’t want to miss.
Source: https://www.tvinsider.com/1198834/countdown-milo-ventimiglia-series-premiere-cameo-darden-dead